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You know I looked at the dip switches but I thought no they would not do that. But hay if they would cut wires and disable a unit like they did I would not put it past them. You know I'm not a person that holds my tongue on stupidity. I meet one of these guys on a roof about 120 miles from here and was talking about another issue they made for me and how I solved it. He laughed and told me he was helping out in the area at the time. I told him he was an
Idiot and needed to find another line of work. Because of people like him is why we have issues.

Just wanted to update.
Found all cut wire. Found that when I jump the comp contact out on board comp runs same with cond fan . When I jump blower out it trips the trans fuss hence is why it was tripped when I arrived. Issolate board ( unplugg blower contactor ) it still tripped trans. I conclude it must be a shorted relay in board.

Just wanted to update.
Found all cut wire. Found that when I jump the comp contact out on board comp runs same with cond fan . When I jump blower out it trips the trans fuss hence is why it was tripped when I arrived. Issolate board ( unplugg blower contactor ) it still tripped trans. I conclude it must be a shorted relay in board.

I gotta tell you, I'm having trouble with this.

I work on these units a LOT, and I'm catching things that are not making sense to me.

Found that when I jump the comp contact out on board comp runs same with cond fan.

What do you mean by "jump the comp contact out on the board?"

What is a "comp contact," and where on the board is it located?

Do you have pictures you can post?

The first thing I would do is make certain that the "unit test" and "shift" DIP switches are to the LEFT.

Are they?

How are you "jumping" the blower out? Are you placing a jumper on the wires at TB1?

What does "unplug the blower contactor" mean? Where did you do that? Do you mean remove the coil wires from the contactor????

In cases like this, communicating accurately is CRITICAL to our being able to help you.

I am sorry about the short terminology, i was riding and it hit me that i have not updated my findings. I was typing on my iphone and not a very good typist. I had to keep things short and sweet. I am sorry for the inconvenience.
On the right side of the board MI-7 Pt# 70M2101 there is a line of relays. Under these relays is were the 24v Comes into the board and powers the contactors for your Indoor blower, Condenser fan motor and the compressor. On the far right there is a red wire (24v) I put a wire in that wiring plug and jumped it to the I think 3rd or 4th wire to the left. This allowed the compressor contactor to engage. Then I went to the wire next to that one and it engaged the condenser fan motor. When i went over to the wire that was coming of that board and going to the indoor blower contactor it tripped the transformer fuss mounted on the transformer. I took the wires off of the contactor for the indoor blower motor because i knew that when i pushed in the contactor the Indoor blower would run. Although this does not count a shorted contactor out. So by taking the coil wires off of the indoor blower contactor i then issolated the indoor blower relay on the board. I then tried puttin power on the indoor blower relay on board and the transformer tripped again. Seeing how the wires coming of the board and going to the indoor blower contactor coil were off of the contactor. I came to the conclusion that the relay on the board or something on that board has some type of a short.
As far as i could tell all dip switches were to the left except the second down it was to the right allowing diagnostic codes to show I think don't hold me to that. But when I was there I made sure they were set the way the chart on the door said to set them.
Any thoughts let me know. The worst mechanic i know is a mechanic that thinks they know everything. I am a 41 year old second generation HVAC Mechanic that has seen and done a lot of things. But I still learn things. And forget. Its actually been about ten years since i have worked on anything this small. But after all they are all the same some just bigger.
Thanks,

I am sorry about the short terminology, i was riding and it hit me that i have not updated my findings. I was typing on my iphone and not a very good typist. I had to keep things short and sweet. I am sorry for the inconvenience.
On the right side of the board MI-7 Pt# 70M2101 there is a line of relays. Under these relays is were the 24v Comes into the board and powers the contactors for your Indoor blower, Condenser fan motor and the compressor. On the far right there is a red wire (24v) I put a wire in that wiring plug and jumped it to the I think 3rd or 4th wire to the left. This allowed the compressor contactor to engage. Then I went to the wire next to that one and it engaged the condenser fan motor. When i went over to the wire that was coming of that board and going to the indoor blower contactor it tripped the transformer fuss mounted on the transformer. I took the wires off of the contactor for the indoor blower motor because i knew that when i pushed in the contactor the Indoor blower would run. Although this does not count a shorted contactor out. So by taking the coil wires off of the indoor blower contactor i then issolated the indoor blower relay on the board. I then tried puttin power on the indoor blower relay on board and the transformer tripped again. Seeing how the wires coming of the board and going to the indoor blower contactor coil were off of the contactor. I came to the conclusion that the relay on the board or something on that board has some type of a short.
As far as i could tell all dip switches were to the left except the second down it was to the right allowing diagnostic codes to show I think don't hold me to that. But when I was there I made sure they were set the way the chart on the door said to set them.
Any thoughts let me know. The worst mechanic i know is a mechanic that thinks they know everything. I am a 41 year old second generation HVAC Mechanic that has seen and done a lot of things. But I still learn things. And forget. Its actually been about ten years since i have worked on anything this small. But after all they are all the same some just bigger.
Thanks,

1) Because wires were cut by the other guy, I would use the diagram to physically trace the wires going to the blower contactor from the board connector plug, to make sure the short is not in the wiring repair.

2) I would remove the blower coil wires from the contactor and

a) measure the coil resistance, and compare it to a known good coil, usually between 8 and 10 ohms on a multimeter.

b) using TB1, the contact strip in the left hand side of the blower compartment, jump R to G.

If you have not opened the blower door and investigated this area, do so, because they may have done something there, too. You can find a reference to TB1 on the sticker inside the door, and the connection numbers are shown vertically and somewhat out of order. There are little numbers inside squares that indicate the terminal numbers of the strip. Find the function you want (R, G, Y1, etc) and its associated number, and go from there.

Having checked TB1, and jumped R to G, apply power to the unit with the blower contactor coil wires disconnected from the coil terminals. If you have an ammeter with an "inrush" button, you could put it on the 24 volt power feed to the board and see how much the current spikes.

Before ordering an expensive board, I would pull it and look at it very carefully, in good light and with reading glasses on if you use them. Look for any damage, discoloration, or lifted circuit traces on both sides.

With the board out of the unit, use solid hookup wire to connect the incoming 24 volt feed that enters the board, and connect it to the blower output wire that goes to the contactor. Create a ground path for the contactor coil, and try to use the wiring harness as a part of it. Connect the coil and power up the unit, with your TB1 jumper R to G still in place. Does the blower coil pull in, and the breaker hold?

If "no" for the breaker remaining closed, after all this testing, I might be inclined to order a board. If I was onsite with you, I could probably become inspired to make some additional tests, but at this level of distance from the situation, I'm not sure what those tests would be. I'm only unsure because wires were cut, and more than one tech was in there. Truthfully, I'm the kind of guy that would want to hand-trace every wire that connects to that board, and ensure the repair integrity and routing, because a couple of hours of my labor is pretty inexpensive when compared to that controller.

I did take the coil wires off of the blower contactor. And made sure the Resistance was good on coil. The coil wire comes off the board to a small TB below the board and is the only wire on it and then goes over to the contactor.

I searched every wire throughout the unit 4 hr process to be sure there were no other wires cut.

I jumped the g and r on the TB at the blower And nothing happened. Which there was power coming back on green because this would be from the t-stat to the board and the G light on the board is on as well as cool. This is my concern the board goes through its proper sequence of operation and nothing comes on. I thought that may be i had a common not making contact or cut. Thats when i Starting the search for more wires being cut. After I was satisfied there were no other wires cut I moved to the jumping out process.

Also I took board out and glanced at it, it appeared fine. There was a little discoloration around the bottom but nothing out of they just thought it was age.

I did take the coil wires off of the blower contactor. And made sure the Resistance was good on coil. The coil wire comes off the board to a small TB below the board and is the only wire on it and then goes over to the contactor.

I searched every wire throughout the unit 4 hr process to be sure there were no other wires cut.

I jumped the g and r on the TB at the blower And nothing happened. Which there was power coming back on green because this would be from the t-stat to the board and the G light on the board is on as well as cool. This is my concern the board goes through its proper sequence of operation and nothing comes on. I thought that may be i had a common not making contact or cut. Thats when i Starting the search for more wires being cut. After I was satisfied there were no other wires cut I moved to the jumping out process.

Also I took board out and glanced at it, it appeared fine. There was a little discoloration around the bottom but nothing out of they just thought it was age.

The lights on the lower left hand corner of the IMC show incoming calls. They don't represent whether the board has decided to enable an output.

Does this unit have the economizer add-on board that lives on standoffs on the left hand side, above those LED's?

Rotate the min pos and make sure the dampers move to full open when the min pos is fully clockwise. Then, set it back to a point just off of the stop at the 7 o'clock position, maybe at 8 o'clock. This allows some fresh air in.

Set the enthalpy to a little past "C".

Now.

Let's see how the unit responds to a test.

Place both the "unit test" and the "shift" DIP switches to the right. Wait until the display stops flashing.

The black square button is used to step through and enable different parameters. Short presses step through the choices, and longer presses cause some change in the parameter that is displayed.

Use the black button and use short presses, one at a time, to make the display say "C 1 1" then press and hold the black button to make two decimal points appear, then release. This tells the unit to run all stages of cooling. In your case, only one compressor is installed, so it should come on. The compressor AND the indoor fan should run. If the breaker pops on the transformer, I would do one more test. Remove the plugs from the economizer board, and remove the board from the IMC. Repeat the test. If the breaker still pops, I'd replace the IMC.

troubleshooting with a laptop

Originally Posted by slctech

No such thing as a E01 on a Lennox IMC board. Like you said it is probably a c01 which means the unit is receiving a first stage call for cooling. Need to double check all the dip switch settings and will need to double check ALL the ECTO settings. Have a feeling that company XYZ was in there playing around and screwed up something in the ECTO settings. Older versions of the IMC may snap back to default on a power bump. If that is the case, may be getting a call for heat but the ECTO setting is basing itself on remote sensor and not conventional thermostat. Need a laptop and plug into the thing...SOOOO much easier. Takes special connections, but the LC program is free from Lennox can be downloaded from their commercial site.

Could you please tell me more about plugging in with a laptop? is this all required is a laptop and LC software? How does it work? Thank you.